Comments on the proposed conservation of usage of Drosophila Fallén, 1823 (Insecta, Diptera) 4 (Case 3407)

The Commission is asked by van der Linde et al. (BZN 64: 238–242) to preserve the binomen Drosophila melanogaster Meigen, 1830. Some obvious points of the application should be stressed and some weak points reviewed.
1. Nomenclatural rules (the Code) regulate nomenclature, i.e. the rules govern how names are used to label recognized taxa formally at family, genus and species level in the Linnean and other systems.
2. The Code is concerned with formation, usage, availability and validity of names, criteria of publication, determination of authorships and dates of publication, and provides the means for maintaining the universality and continuity of usage and meaning of the names, and how to solve potential conflicts.
3. The Code deals largely with the nominal taxa (= nomenclatural taxa), i.e. taxa having their minimum contents linked to their name-bearing taxa of lower rank, or, in case of species-group taxa, to mandatory type individuals. The nominal taxa, in contrast to taxonomic taxa, do not have limits.
4. Taxonomists have freedom of action, i.e. they may, within the framework of voluntarily maintained provisions of the Code, split, unite, interpret, include, exclude, change the ranks of (upgrade or downgrade) existing taxonomic taxa and establish new ones in accordance with progress in knowledge, accepted theory of classification, or even their own ideas. Nobody is obliged to follow these researchers’ decisions.
5. If asked, the International Commission of Zoological Nomenclature, is obliged by voting or usage of its Plenary Powers to solve any resulting or threatening nomenclatural problem, which is not or cannot be covered by the Code, even if this means deviating from its provisions.
6. In theory, nomenclature should be completely divorced from taxonomy. In practice (see 4 and 5 above) there is an overlap, because nomenclatural decisions by individual zoologists, as well as those of the Commission, involve mostly the names of the taxonomic taxa. However, the principle of taxonomic freedom (see 4 above) is always maintained.
The present problem is how to preserve continuing usage of the well known binomen Drosophila melanogaster which is threatened by the intended split of the paraphyletic genus Drosophila into several smaller monophyletic genera (realized mainly by upgrading several of its subgenera) as suggested by a group of molecular phylogeneticists (van der Linde et al., BZN 64: 238–242). This is basically a taxonomic problem with nomenclatural consequences. Drosophila melanogaster, along with several other con-subgeneric model species, would then be classified within the genus Sophophora (presently a subgenus of Drosophila), unless the Commission changed the fixation of the validly designated type species of Drosophila. I should like to provide the following comments.
(1) The preservation of the binomen Drosophila melanogaster is desirable since it has been used in numerous publications and is well known to biologists as well as many outsiders and laymen. The arguments, however, focused as they are on Drosophila melanogaster and its allies alone, are short-sighted. The consequences for the nomenclature of the whole family DROSOPHILIDAE should be taken into account. The argument that in many general scientific papers the names ‘Drosophila’, ‘drosophila’ and ‘fly’ stand for Drosophila melanogaster can hardly be taken seriously; moreover ‘fly’ may often stand for Musca domestica or Calliphora erythrocephala.
(2) To approve the application would be to provide institutionalised support for one of several possible and coexisting hypotheses on the phylogeny of drosophilids. But hypotheses, by their very nature, may come and go and, after rigorous testing, may be replaced by better ones or at least by a set of alternatives. The Commission cannot discriminate between ‘superior’ and ‘inferior’ hypotheses, phylogenies and classifications – its role is to provide a formal framework of rules.
(3) The authors of the application are wrong in considering that their method of classification is the only correct one and must be accepted by the Commission. Freedom of taxonomic thought and action should override all other considerations.
(4) Amelioration of a classification found to be formed by sets of small monophyletic taxa, which are actually ingroups of one or more paraphyletic larger taxa, may be achieved basically by two procedures: (a) an analytic one – by splitting the paraphyletic taxon/(taxa) into two or more monophyletic taxa accompanied by inclusion of their ingroups, formerly classified as coordinate taxa (this is the taxonomic procedure suggested by the authors of the application); or (b) a synthetic one – to combine all the taxa in a comprehensive monophyletic taxon, in this case Drosophila, and to build up its structure to include only monophyletic subordinate taxa. This is the course I would recommend; a tacit agreement of all the researchers involved would be a prerequisite to such a solution. The argument that Drosophila (s.l.) would then be too large is of no scientific (and definitely of no nomenclatural) importance – how many well known and large genera (e.g. Papilio, Carabus) do we all know and use?
(5) Drosophila melanogaster is an important binomen. However, more important, in a long-term view, is the independence of nomenclature from current taxonomic/phylogenetic hypothesis and paradigm. Therefore, I recommend rejection of the application.